Typically, a commercial AC power supply is rectified, filtered and converted into DC power source for many electronic products. Although the input AC voltage is sinusoidal, the waveform of the input current is pulse due to the operation of rectifier diodes and a filtering capacitor. The input current (also referred as a harmonic current) relative to the power consumption represented by a power factor is reduced. The reduced power factor indicates that energy resource of the earth has been wasted. Under such circumstances, some regulations about power factor and harmonic current have been provided, such as IEC-1000-3-2 by IEC (International Electrochemical Commission).
The typical means for improving harmonic current includes an active type power factor correction circuit and an inductor power factor correction circuit. Since the circuit layout is simple and cost-effective, the inductor power factor correction circuit is widely used. Because the inductor power factor correction circuit is implemented under a low frequency and high current, the typical inductor is formed by using an EI type core wound around coils. Such inductor has disadvantages of high inductance leakage and high volume.
Therefore, the present invention provides an improved winding structure of an inductor used in an inductor power factor correction circuit so as to overcome the problems described above.